Unable to see seat reservation my friend made

That's normal. Reservations are separate from the pass. If your friend wants to share them, she can send you the PDFs, or the booking references to import in the operators’ apps (works for some operators).

FYI, the best reservation guide is this page:

https://www.seat61.com/interrail-and-eurail-reservations.htm

Hello,

I have the same problem, my friend who booked the reservation sent me the PDF of the reservation, but then I cannot activate my pass because there is not trip in it. How can I activate mt pass if the reservation was made by another person?
Thank you in advance,

Riccardo

Whether you have a reservation or not (and who booked it) is not relevant for activating your pass.

Activating your pass should always work. If you don't have a trip yet, then you can create one in step 2 of the activation procedure:

https://www.interrail.com/en/interrail-passes/interrail-mobile-pass/getting-started

Are you following the steps outlined in this procedure? At which exact step are you stuck? Could you post a screenshot of any error that you see, or of the screen where you are stuck?

Sorry, I thought that I needed reservations to create a trip. Is it possible to create more trips within the same pass?
Kind regards,

Riccardo

Of course you don't need a reservation to create a trip. There are many trains you can't book, so such a requirement wouldn't make sense.

One pass needs to be connected to exactly one trip. That trip will eventually contain al trains you'll use with your pass.